In general, a transmission in a vehicle is supplied with oil in order to lubricate rotary bodies such as a torque converter, a gear, and a bearing. Hydraulic oil is used for a variety of hydraulic mechanisms such as a clutch and a brake. Coolant is used to cool an engine.
When such oil or coolant is increased in temperature, an overflow phenomenon is generated to thereby cause malfunction of the devices. Therefore, a cooler or a heat exchanger is used to maintain the temperature of oil or coolant below a certain temperature.
As shown in FIG. 1, conventional TOCs (Transmission Oil Coolers) each include a first manifold 120 which supplies fluid introduced from the outside to a cooling unit 110, the cooling unit 110 which cools the fluid supplied from the first manifold 120 by heat exchange action, and a second manifold 130 which collects and discharges the fluid discharged from the cooling unit 110.
The fluid introduced from a transmission into the first manifold 120 via a supply passage 125 is cooled by heat exchange with outdoor air during passing through the cooling unit 110, and is then discharged to the second manifold 130. Subsequently, the discharged fluid passes through a discharge passage 135 and is then circulated to the transmission. An example similar to the structure shown in FIG. 1 is disclosed in U.S. Pat. No. 7,073,570.
The conventional cooling unit 110 has a maximum length which is allowable in a limited space such as an engine room of the vehicle. Accordingly, there is a problem in that fluid significantly drops in pressure when reaching the second manifold 130 from the first manifold 120. Since this adversely affects a pumping device for forcibly circulating fluid, heat exchange efficiency may be reduced.